Pelvis, pelvic girdle and hip region Flashcards
What are the functions of the pelvis and hip joint?
Weight-bearing in standing and sitting, locomotion
what does the pelvis comprise?
pelvic girdle (two hip bones) and sacrum
what are the components of the hip bone?
Ilium, ischium and pubis
what holds together the components of the hip bone?
triradiate cartilage
what joints is the hip bone involved in?
sacroiliac joint, pubic symphysis, hip (coxal) joint
what are the two parts of the sacroiliac joint and what do they articulate?
Fibrous syndesmosis: iliac tuberosity with sacral tuberosity and attachment of sacroiliac interosseous ligament
synovial plane joint: iliac and sacral auricular surfaces
What is sacral nutation?
Body weight forces the base of the sacrum anteriorly and inferiorly. Ground reaction forces the apex posteriorly and superiorly. This results in the anterior tilt of the sacrum relative to the ilium (known as sacral nutation)
What is the pubic symphysis comprised of?
Pubic bone articular surfaces lined by hyaline cartilage, interposed by fibrocartilage disc
What type of joint is the hip joint?
synovial ball and socket multiaxial diarthrosis (can perform movement in 3 planes)
What are the parts of the acetabulum?
Lunate surface (crescent shaped) is the weight bearing surface and is covered in articular cartilage. The acetabular fossa is the depression in the centre and it is non weight bearing. The transverse acetabular ligaments replaces the lunate inferiorly
What is the frontal plane alignment of the femur?
Femoral angle of inclination: the angle formed between the neck of the femur and its shaft (normal is about 125-135 degrees)
What is the transverse plane alignment of the femur?
Femoral anteversion: angle formed between the neck of the femur and condyles (normal is 15 degrees) ante = forwards
Describe the hip joint alignment.
The head of femur and acetabulum both project anteriorly, therefore femoral head is directed toward anterior-superior acetabulum. This causes an exposed femur head surface in standing. This results in greater hip flexion ROM than hip extension ROM. During flexion and abduction, the. head of the femur is moved deeper into the acetabulum
What are the consequences of femur angle of inclination and hip joint alignment?
Joint reaction force is more vertical on the neck of femur which places bending moment on NOF, creating tension on the lateral side and compression of the inferior side.
What is the differences between coxa valga and coxa vara?
Coxa valga = lateral orientation of the shaft of femur relative to NOF (>135 degrees)
COxa vara = medial orientation of the shaft of femur relative to NOF (<120 degrees)
What are the consequences of coxa valga and coxa vara alignment of the femur?
Coxa valga: Joint reaction force is more compressive along NOF, glut med moment arm is reduced (therefore more muscle fibres of other hip abductors need to be recruited), and orientation of head of femur is directed more superiorly
Coxa vara: Exposes greater bending moment therefore greater shear force, glut med moment arm is greater therefore increases efficiency of force produced by muscle, orientation of the head of femur is more medial and deep
What are the hip flexor muscles (and what are the most effective of these)?
Psoas, iliacus and rectus femoris (most effective hip flexors)
Others include: Tensor fascia latae, sartorius (sartorius is also pretty effective), adductor longus, pectineus
What are the functions of iliacus and psoas major?
Hip flexion. As well as this, when they contract they produce a posterior force on the anterior aspect of the femoral head which maintains the position of the femoral head in the acetabulum during hip flexion.
What are the hip extensors? (mention which ones are most efficient)
Most efficient hip extensors include gluteus maximus, long head of biceps femoris, semitendinosus and semimembranosus. Adductor magnus also has a component that contributes to this action.
What are the abductors of the hip?
Gluteus medius (main abductor; most torque produced), gluteus minimus, TFL, (sartorius can produce abduction but not much torque produced)
What are the hip adductors?
Pectineus, adductor brevis, adductor longus, adductor magnus, gracilis
What are the hip lateral (external) rotators?
Most efficient = gluteus maximus and posterior gluteus medius in hip extension)
Others include piriformis, obturator internus, superior gemellus, inferior gemellus, quadratus femoris, obturator externus
What are the medial (internal) rotators of the hip?
There are no dedicated hip medial rotators (no muscle’s main action is to internally rotate the hip). However, in hip flexion, all of gluteus med and min; piriformis. In hip extension, anterior glut med and min, semimebranosus and semitendinosus
What are the actions of the different segments of gluteus maximus?
all segments = hip extensors + hip lateral rotators
upper segments = hip abductors
lower segments = hip adductors
